The invention relates to a lift valve in accordance with the preamble of claim 1.
In relatively large installations, lift valves are used almost exclusively with a flange casing. In the flange casings, the connection sides of the casings are provided with protruding flange plates which have a sealing face and interact with corresponding counter-flanges located on the pipeline elements to be connected. Sealing elements are arranged between the flanges in the region of the sealing faces, screw elements which penetrate the flange plates producing the necessary prestressing forces for a sealing connection. In order to ensure that the screw elements can be accessed, the flange plates are arranged exposed on the lift-valve casing. The significant advantage of such lift valves with flange elements is also that easy replacement is possible when required. By loosening the screw elements, the lift valve can simply be pulled out between the flanges of the adjacent pipelines and installed between the flanges and sealed again in the same way.
So that installation manufacturers can be equipped with respectively suitable fittings for various applications, there are further casing designs. In the case of sleeve valves, pipeline ends are screwed or soldered into the sleeves. In the case of other valve designs, the connections are designed as welding ends to be welded to associated pipeline ends in a fluid-tight fashion. The effort for the installation and removal of such valves is considerably greater. Owing to the different design series, these various designs require a large logistical outlay both on the part of the manufacturer and on the part of the customer.
GB-A 1 359 755 shows a lift-valve design which is intended to allow costs to be reduced and to involve a reduced material outlay and reduced processing effort as well as a simple design. For this purpose, a valve is proposed in whose tubular casing a cylindrical passage is provided. This passage serves to receive a replaceable cylindrical insert which abuts against a shoulder within the tubular casing. The insert contains flow conducting paths for a fluid which is to be blocked off and a valve seat and requires positioning elements which can be used to align its position within the casing precisely and hold it in this position. In a corresponding way, a cap, in which a replaceable insert, which receives the activation elements of a valve stem, is mounted, is arranged in the outer cylindrical casing of the valve. This solution is suitable both for valve casings which are clamped in between flanges and for casings which are equipped with flange plates. In comparison with a conventional valve, this design is however considerably more expensive since, owing to the casing which is complicated to fabricate, and to the additional insert, the processing outlay is substantially greater than that for cast valve casings. In addition, the material-removing processing of the inserts give rise to serious material losses, and, as a result of the inserts, connection points arise which also have to be sealed and at which corrosion problems may occur under certain circumstances. Furthermore, this valve has a comparatively large overall length. Therefore, long screw bolts are required for the clamping in procedure. Said screw bolts give rise to significant handling disadvantages, since a large amount of space is required to remove and install the valve, and this is not available in many installation situations.
Existing standards define the overall lengths of the lift valves. In principle, a lift valve comprises a casing region, which contains a movably arranged closure element, and has an associated valve seat in a dividing wall. Flange plates are arranged on both sides of this casing region using junctions. A medium flowing linearly to a lift valve through a pipeline is deflected, after passing through the first flange in the junction region, in order to pass a valve seat with associated closure element and be directed from a casing junction region lying opposite in the axial direction again to the continuing pipeline. Such a wave-shaped path through a lift valve with vertically arranged stem inevitably increases the overall length of the valve casing and causes flow losses, for which reason lift valves usually have a high flow coefficient .xi.. Said coefficient is usually of the order of magnitude of approximately 4.
Different designs have been developed in order to obtain flow coefficients which are more advantageous for lift valves. One of these designs are so-called slanted seat valves, in which the flow path between the connecting flanges is as linear as possible, into which flow path a closure element which is arranged obliquely thereto dips. The disadvantage of such a design is the oblique course of the valve stem. Depending on the installation position, such a lift valve can be less convenient to use, is more difficult to insulate and has a large overall length.
A lift valve with low flow losses, an advantageous .xi. value of approximately 1.2 and a shorter overall length is the KSB development BOA-Compact, which has made a shorter overall length possible than is the case with traditional lift valves with a valve stem which is arranged perpendicularly with respect to the pipeline. The flange-type designs available on the market require respectively different design series for the different rated pressure levels. This requires a high logistical outlay on manufacture, storage and mounting.
DE-A 20 48 580 presents a valve design which is resistant to corrosive chemicals and has two different overall lengths. The lift valve is implemented in a mixed design, using standardized semifinished products made of special metals, in order to reduce the high costs of the special materials which are necessary. In this respect, FIG. 1 shows a pure welded design, while FIG. 5 shows a short design of the lift valve in which an external, cast housing made of a cheap material which comprises metal or plastic is used. This external housing is provided with a corrosion-resistant internal housing. In its dimensions, the internal housing corresponds, with its closure part and the functional elements which interact with it, to the corresponding parts of the housing design according to FIG. 1. Thus, given two different designs, the manufacturing costs of the parts which are composed of special metals, can be reduced owing to the relatively large number of identical parts.
A round massive valve cone, which is pressed into an eliptical opening of a valve seat which is arranged obliquely in the housing, is intended, whatever its state of wear, to have a sealed termination at the edge of an elliptical opening which forms the valve seat. A prerequisite of this is a rotatable arrangement of the massive valve cone over its lifting range in order to come to bear against other parts of the seat face of the valve cone in each case.
The short valve design which is shown in FIG. 5 of DE-A-20 48 580 can be used only in conjunction with 4-hole flanges. In the case of relatively large flanges or when it is used in pipeline systems with relatively high pressures, which require flanges with more than 4 screwed holes to be used, the clamping-in design which is shown can no longer be used. This is because the flange screws which are used to hold the armature between two flanges cannot be guided past the housing in the region of the valve stem owing to the reciprocal hole for the round valve cone, said hole being located in the housing and running perpendicularly with respect to the through-flow direction. The overall length of the lift valve in FIG. 5 which has a short effect on first impression, is almost 60% larger than the corresponding nominal diameter.
The invention is based on the problem of developing a lift valve which reduces the aforesaid outlay and has a versatile field of application with low flow losses. The solution of this problem provides for a lift valve in accordance with the invention as described hereinafter. The advantages of this design are manifold.
The entire lift valve is considerably shorter and lighter in weight and therefore permits significantly more convenient mounting. The lift valve can be clamped in in an extremely simple way between the flanges of pipelines to be connected. The flanges which are normally provided on the casings of lift valves for connecting to counter-flanges of a pipeline are no longer required for installation purposes. Those casing components which produce a connection to the valve seat region and the flanges are also dispensed with. Instead, only sealing faces are arranged on the casing which only surrounds the closure element. Said sealing faces, which are also known as sealing strips when seals are used, are integrated directly into the casing component which surrounds the closure element and its travel region. The end sides of the casing form at the same time the sealing faces for pipeline elements which are to be connected to the lift valve. The sealing faces thus lie in the direct vicinity of the closure element, as a result of which it is possible to obtain for the first time lift valves with an overall length whose order of magnitude lies approximately in the region of the nominal diameter or corresponds to the nominal diameter. In terms of a pipeline system, this results in significant savings in pipeline lengths and the use of material. In comparison with conventional lift valves, overall length reductions of 135 mm to 330 mm are obtained in the nominal diameter range from DN 25 to DN 150. Overall length reductions of 100 mm to 60 mm are obtained in comparison with BOA-Compact lift valves, which are already very short. This measure has a positive effect on the use of our natural resources and, moreover, has the further advantage that the lower overall weight makes mounting significantly easier and reduces transport costs.
The overall length of the lift valve is determined by the position of the valve seat and the thickness of the adjoining casing wall. By arranging the valve seat obliquely with respect to the direction of through-flow and to the valve stem, both conical and planar valve seat geometries are possible. The slanting valve seat can either be arranged in a plane or have a spatial curvature. When a closure element which rests on the valve seat is used, junctions for a supporting face have to be provided between the casing wall and the valve seat. Said junctions then form, in conjunction with the closure element, a dividing wall within the casing. It is also readily possible to provide in such a dividing wall or in the junctions another, for example conical, valve seat which interacts with a correspondingly shaped closure element. The valve seat or a wall face or wall face components holding the valve seat extend, for the purpose of reducing the overall length, as a quasi-diagonal connection between the end faces of the casing. In doing so, the connection intersects the pipeline axis, or runs obliquely with respect to the through-flow direction. A short and direct connection of the end faces of the casing to the valve seat or a casing component containing the valve seat is essential. This makes it possible to displace the end faces of the casing in the direction of the closure element, resulting in a significant reduction in the overall length. In comparison with the closure-element length which is projected onto the pipeline axis and can be measured in the axial direction, the distance which can be measured between the end faces of the casing in the same direction is only 25% to 50% longer. In comparison with the previously known solutions, this constitutes an only slightly larger distance and makes it possible, for the first time, for the lift valve to have an overall length which can be measured between the end faces of the casing and which preferably corresponds to the respective nominal diameter of a size of lift valve. This is determined essentially by the thickness of the casing wall, the length of the valve seat and the size of the junctions between the valve seat and the casing.
The dividing wall, which is otherwise customary in the case of lift valves, is composed here almost exclusively of the valve seat for the closure element and the junctions adjoining the valve seat and leading into the end sides of the casing or into the surrounding casing wall. This short overall length also results in a further significant advantage. The overall length of a lift valve constitutes a considerable cost factor in the construction of buildings. Buildings must have spaces in which central distribution stations are located and from which the pipeline systems located in the building for heating systems and air-conditioning systems, and water supply systems, are controlled. In the spaces of the distribution stations, the distribution lines of the pipeline systems usually extend vertically. Relatively high spaces are necessary in order to be able to install in the vertical distribution lines a corresponding number of the lift valves which are fabricated in the usual standard overall lengths and have good throttling and regulating properties. Using the new and considerably shorter lift valves, it is possible to construct lower storey heights for the distribution stations. As a result, the construction costs can be reduced and the utilization rate of a building can be improved.
In order to obtain a low flow resistance value, the seat cross-section of the lift valve corresponds approximately to the order of magnitude of the connection cross-section of the pipeline, and thus approximately to the nominal diameter. By throttling the valve cross-section in comparison with the pipeline cross-section, shorter overall lengths would also be possible, but this would degrade the flow coefficient .xi..
According to a further refinement of the invention, the casing is of annular design. Such a shape is very easy to fabricate and requires a minimum of material. The end sides of the annular casing serve at the same time as casing sealing faces. In principle, the casing comprises an annular region, an obliquely arranged valve seat or an obliquely arranged dividing face containing the valve seat. The latter can be arranged in the annular casing region in a materially joined, frictionally engaging or positively locking fashion. In a region which is located above this, usually referred to as a casing neck, the closure element and the valve stem are arranged.
In accordance with a further refinement of the invention, the casing and the casing neck are of single-component or multicomponent design. In the case of a single-component design, it is possible to insert the closure element into the casing from the casing sealing-face side. A two-component or multicomponent design also permits a different mounting method, for example through an opening for the casing neck.
Further refinements of the invention, according to which a wall which bounds the travel movement of the closure element is designed so as to be concave towards a space receiving the closure element, and a closure-element face which abuts against the concave wall is of convex design, permit a space-saving arrangement of the closure element within the surrounding casing. The bulges in the wall faces provide a further physical clearance. During the normal travel movement for opening the full flow cross-section, the closure element moves from the valve seat into the space. As a result of the bulges, the closure element can migrate further upwards in the space without being impeded by the screw elements bounding the space or by the required wall thickness.
According to a further refinement of the invention, the lift valve is constructed as a wafer-type valve. The lift valve can thus be clamped in, in an extremely simple way and independently of the permitted pressure levels, between the flanges of pipelines which are to be connected. The sealing faces on the flanges use flat seals to interact with the casing end faces located in the direct vicinity of the closure element. And screw elements which connect the flanges to one another press the pipe-line flanges located on each side of the casing against the casing and clamp said casing tightly between them.
For those applications in which such a lift valve is also intended to be used as a termination fitting for terminating a pipeline, the casing can also be designed as a single-flange casing. This makes it possible to form a supporting surface for screw elements which press the valve casing against the end of a pipeline.
In order to ensure the short overall length, flanges or flange components are arranged on the casing in the region between the end faces of the casing, parts thereof being arranged in a plane which intersects the valve seat. In the case of an externally symmetrical casing design, the valve seat is arranged asymmetrically within the casing, which can result in the situation in which a flange or parts of said flange on one side of the casing are located directly in front of the plane of the valve seat, and on the other side of the casing the flanges or flange components are arranged in a plane which intersects to the valve seat. In order to ensure, when mounting such a lift valve as a termination fitting, that the mounting means do not protrude beyond the valve, the flanges or flange components are arranged set back with respect to the end faces of the casing, at least by a measure corresponding to the height of a screw head or a nut.
The lift valve can also be installed in a pipeline system in which clamp elements connect the casing to a pipeline. The end faces of the casing would then also abut directly against the end face of a pipeline and, depending on the mounting system employed, a plurality of clamp elements, or clamp elements designed as joint components, may be used. For this purpose, grooves or projections as supporting surfaces for the clamp elements are arranged on the circumference of the casing in the region of the casing end-faces. Such connecting techniques are frequently found in the field of the food industry.
DE-B-23 11 865 discloses a lift valve which is designed as a diaphragm valve and is composed of a lower casing part which is made up of three components. The division into three was performed in order to obtain cost-effective injection-moulded parts with approximately identical single weight. A center casing component which is provided with a sealing web has spatially extending flange faces against which flange ends abut, with the intermediate connection of a likewise spatially extending toroidal sealing ring, and are connected to the centre casing component by means of tie rods. This valve is operational only when all three parts are combined.
In contrast, one refinement of the invention provides for the end faces of the casing to be designed as interfaces for different connecting adapters for the pipeline. And a further refinement provides for the connection adapters to be equipped on the pipeline side with different connection shapes. These may be flanges, welding ends, sleeves or the like. This solution provides a significant simplification in the use of a lift valve. As a result, it is also possible to retrofit the lift valve into an already existing pipeline system or into a pipeline system with different connection systems. The basic design constitutes a completely operational lift valve which can be installed in an extremely simple, problem-free fashion in the most widespread pipeline systems with flange connections. The flanges which are usually used permit such a lift valve to be clamped in without difficulty. Designing the end faces of the casing, which form the sealing faces, as an interface for the attachment of adapters, provides the enormous advantage that simple adapters can be used to adapt the lift valve to other pipe connection systems, and install it there, without difficulty. The adapters are in the form of simple rotationally symmetrical components and can be mass-produced using casting or material-removing processes, or in some other way. If necessary, they can also be fabricated at short notice on request, so that costly stockholding for such components is not necessary. For a manufacturer and its dealers it is sufficient to have the operational basic valve in stock, so that, if required, they can be adapted for use in a wide variety of applications using the simple adapters.
For the use of the lift valve which forms the basic element, a further refinement of the invention has provision for the casing region which surrounds a closure element to be provided between the end faces of the casing with one or more radially protruding receptacles which have openings and are intended for screw elements. Screw elements which connect the flanges can be pushed through the openings or attached thereto. The individual receptacles can also be in the form of projections or flange eyes, each projection being equipped with one or more openings. Such a measure constitutes a further saving in material and permits a lift valve to be connected to different flange designs. The openings can correspond to the various national and/or international flange standards, for example ANSI, DIN, EN and the like. It is also possible to use the lift valve as a termination fitting.
According to another refinement of the invention, a casing component which is penetrated by the valve stem is provided with receptacles for screw elements. This is usually a casing neck or that region of the lift valve casing into which a closure element is moved during the opening movement. The receptacles can be blind holes which receive screw elements. This refinement is used in those cases in which the screw elements cannot be moved past the casing neck laterally owing to a close arrangement of the flange holes.
Likewise, according to a further refinement of the invention, the casing component which is penetrated by the valve stem is provided with thickened portions of material for the arrangement of the receptacles. Usually, this applies only to receptacles arranged to the side of a valve stem. The bearing surfaces of said receptacles and of receptacles which lie opposite one another and which extend parallel to the flange faces of the pipeline flanges to be connected are at a greater distance from one another than the remaining receptacles.
A further refinement of the invention provides for the valve seat to be arranged almost completely in the dividing plane between the pipeline axis and the region of the flow space remote from the valve stem. The closure element and the space which is necessary for the travel movement of the closure element and into which it dips during the opening movement is then always located within the hole pattern for the openings of the flange screw-connections as well as inside the necessary wall thickness of the casing. In the region between the casing neck and the pipeline axis, the space in which the closure element is received during the opening movement of the lift valve and can thus exert only little influence in the flow coefficient is provided.
With the invention it is possible to fabricate an extremely compact lift valve which is advantageous in terms of flow and which can be connected with its casing to an extremely wide variety of flanges and/or flange standards. Furthermore, it is possible to cover an equally large application range with a smaller number of casing variants.